RESUMO
Chagas disease affects approximately 7 million people worldwide in Latin America and is a neglected tropical disease. Twenty to thirty percent of chronically infected patients develop chronic Chagas cardiomyopathy decades after acute infection. Identifying biomarkers of Chagas disease progression is necessary to develop better therapeutic and preventive strategies. Circulating microRNAs are increasingly reliable biomarkers of disease and therapeutic targets. To identify new circulating microRNAs for Chagas disease, we performed exploratory small RNA sequencing from the plasma of patients and performed de novo miRNA prediction, identifying potential new microRNAs. The levels of the new microRNAs temporarily named miR-Contig-1519 and miR-Contig-3244 and microRNAs that are biomarkers for nonchagasic cardiomyopathies, such as miR-148a-3p and miR-224-5p, were validated by quantitative reverse transcription. We found a specific circulating microRNA signature defined by low miR-Contig-3244, miR-Contig-1519, and miR-148a-3 levels but high miR-224-5p levels for patients with chronic Chagas disease. Finally, we predicted in silico that these altered circulating microRNAs could affect the expression of target genes involved in different cellular pathways and biological processes, which we will explore in the future.
Assuntos
Doença de Chagas , MicroRNA Circulante , Cardiopatias , MicroRNAs , Humanos , RNA-Seq , MicroRNAs/metabolismo , Biomarcadores/metabolismo , Doença Crônica , Doença de Chagas/diagnóstico , Doença de Chagas/genéticaRESUMO
Chagas disease principally affects Latin-American people, but it currently has worldwide distribution due to migration. Death among those with Chagas disease can occur suddenly and without warning, even in those who may not have evidence of clinical or structural cardiac disease and who are younger than 60 years old. HCN4 channels, one of the principal elements responsible for pacemaker currents, are associated with cardiac fetal reprogramming and supraventricular and ventricular arrhythmias, but their role in chagasic arrhythmias is not clear. We found that a single-dose administration of ivabradine, which blocks HCN4, caused QTc and QRS enlargement and an increase in P-wave amplitude and was associated with ventricular and supraventricular arrhythmias in mice challenged with isoproterenol, a chronotropic/ionotropic positive agent. Continuous treatment with ivabradine did not alter the QTc interval, but P-wave morphology was deeply modified, generating supraventricular arrhythmias. In addition, we found that repolarization parameters improved with ivabradine treatment. These effects could have been caused by the high HCN4 expression observed in auricular and ventricular tissue in infected mice. Thus, we suggest, for the first time, that molecular remodeling by overexpression of HCN4 channels may be related to supraventricular arrhythmias in acute Chagas disease, causing ivabradine over-response. Thus, ivabradine treatment should be administered with caution, while HCN4 overexpression may be an indicator of heart failure and/or sudden death risk.
RESUMO
In Chagas disease (ChD) caused by Trypanosoma cruzi, new biomarkers to predict chronic cardiac pathology are urgently needed. Previous studies in chagasic patients with mild symptomatology showed that antibodies against the immunodominant R3 epitope of sCha, a fragment of the human basic helix-loop-helix transcription factor like 5, correlated with cardiac pathology. To validate sCha as a biomarker and to understand the origin of anti-sCha antibodies, we conducted a multicenter study with several cohorts of chagasic patients with severe cardiac symptomatology. We found that levels of antibodies against sCha discriminated the high risk of sudden death, indicating they could be useful for ChD prognosis. We investigated the origin of the antibodies and performed an alanine scan of the R3 epitope. We identified a minimal epitope MRQLD, and a BLAST search retrieved several T. cruzi antigens. Five of the hits had known or putative functions, of which phosphonopyruvate decarboxylase showed the highest cross-reactivity with sCha, confirming the role of molecular mimicry in the development of anti-sCha antibodies. Altogether, we demonstrate that the development of antibodies against sCha, which originated by molecular mimicry with T. cruzi antigens, could discriminate electrocardiographic alterations associated with a high risk of sudden death.